Radio transmitters have long been transmitting digital data telegrams according to the RDS standard in addition to audible broadcast signals. These data telegrams contain identifiers (PS) for the transmitter name, e.g., NDR1, NDR3, FFN, ANTENNA and identifiers (PTY) for the type of program, e.g., sports, news, classical. The latter identifier (PTY) is transmitted in each RDS group, i.e., 11.5 times per sec, and therefore it appears every 80 ms, whereas only the zero group is used for transmission of the transmitter identifier (PS), and the identifier is fully transmitted only after four consecutive group signals. Since the zero group is transmitted by the radio transmitter only 2-4 times per second on the average, the transmitter identifier appears on the display after 1-2 seconds at the soonest.
There are conventional devices, e.g., the Blaupunkt Berlin car radio which also analyzes the PTY identifier. The PS identifier is analyzed today by practically all RDS receivers to display the transmitter name.
The Blaupunkt Berlin car radio has a menu mode where a certain type of program can be selected and then a search run samples successively the transmitters that can be received and are transmitting a broadcast of the selected type of program. On a display with a large display capacity, the header shows the type of program selected and below that the transmitters identified are displayed in a list.